Abstract:Poly(propylene phosphate) solutions were studied and found to display a sol-gel transition temperature that can be controlled by adjusting the concentrations of polymer and Ca2+ so that the therapeutic delivery cargo is liquid at room temperature but solidifies at the in vivo temperature of 37°C. The gels showed rapid gelation kinetics but instability at high shear strains. Ion exchange between buffer and gel induced a dissociation of the network with time, leading to a zero-order controlled release of plasmid DNA or lysozyme.